Add number_with_delimiter and remove unnecessary dara placement for groups page

app/views/dashboard/_groups_head.html.haml

 .top-area
   %ul.nav-links
     = nav_link(page: dashboard_groups_path) do
-      = link_to dashboard_groups_path, title: 'Your groups', data: {placement: 'right'} do
+      = link_to dashboard_groups_path, title: 'Your groups' do
         Your Groups
     = nav_link(page: explore_groups_path) do
-      = link_to explore_groups_path, title: 'Explore groups', data: {placement: 'bottom'} do
+      = link_to explore_groups_path, title: 'Explore groups' do
         Explore Groups
   - if current_user.can_create_group?
     .projects-search-form

app/views/shared/groups/_group.html.haml

@@ -15,11 +15,11 @@
   .stats
     %span
       = icon('home')
-      = group.projects.count
+      = number_with_delimiter(group.projects.count)
 
     %span
       = icon('users')
-      = group.users.count
+      = number_with_delimiter(group.users.count)
 
   = image_tag group_icon(group), class: "avatar s46 hidden-xs"
   = link_to group, class: 'group-name' do